[X] [Charge Chance] - we should try to withhold judgment until we have the facts, and therefore we should start by collecting as many facts as possible. We should be flexible if we come across something that seems important, but a generally bottom-up approach seems suitable for this. Start by learning about the harvest, the local terrain, and the families closest to the harvest - what exactly do they do for a living, how does the harvest's success or failure affect their income, what are their cultural and religious beliefs, who do they trust or mistrust, who do they depend on and who depends on them? Move up to learning about the families who are a couple steps removed from the harvest, answering the same questions. Finally, investigate the nobles, since you should now have enough background info to catch the half-truths and white lies that nobles tend to tell. (Bonus, maybe they'll be caught off-guard if they do have something to hide, since we'll have spent a while not directly investigating them first and they may have allowed themselves to believe they're beyond suspicion.) After all the local families have been investigated, the Drovers should have arrived, and we can investigate them as well. Hopefully by this point some patterns will have emerged, and we will have a better idea of who has motive and means to ruin the harvest - if anyone. The truth may not be what we expect and it would be irresponsible to ignore possibilities like (1) the adventurers are being hired by someone from another town (2) the adventurers are acting on their own initiative to benefit themselves somehow (3) there are no adventurers, the monsters are acting on their own initiative; perhaps something drove them to migrate, or a map glitch gave them access to the area (4) the adventurers are being framed for someone else's actions (5) someone in town is being framed for hiring adventurers by their real employer.
[X] [Charge Chance] - We're still trying to establish motive. For now, pull at the threads of "origins of the public perception of Jatu's piety" and "why is shepherd an insult that someone would use for Tayeb". Try to get multiple sides of the story that Iustina told us. In fact, try to get multiple sides per family; if there's a lone wolf culprit, they might not tell us the same story that their kin would. When inspecting the fields, find out whose were actually damaged, and more importantly when; Guy Fox knew we were coming, so it's possible the attacks were staggered such that we'd arrive in time to stop the ones that would actually harm the perpetrator.